Q: Which type of infrarenal abdominal aortic aneurysm (AAA) is more dangerous? (choose one)
A) Fusiform or B) Saccular
Answer: Saccular
Most (90%) infrarenal aneurysms are fusiform in appearance. It bulges or balloons out on all sides of the aorta.
A saccular aneurysm is balloon-shaped with a narrow neck, bulges out from the main arterial segment (bulges or balloons out only on one side) and is the most likely to rupture.
A pseudoaneurysm, or false aneurysm, is an enlargement of only the outer layer of the blood vessel wall. Sometimes, a tear can occur on the inside layer of the vessel resulting in blood filling in between the layers of the blood vessel wall, creating a pseudoaneurysm.
